Abstract: Based on the A2a and B2a climatic scenarios for both the baseline period (1961-1990) and the future scenario periods (2010-2039,  2040-2069, and  2070-2099) from the Hadley Centre’s General Circulation, and by using Delta method, WGEN downscaling methods, and Canadian Forest Fire Danger Rating System, this paper classified the forest fire dangers in Great Xing’an Mountains region of Heilongjiang Province, Northeast China, predicted the changes of the forest fire danger rating in the period 2010-2099 relative to baseline period (1961-1990), and analyzed the uncertainty of the longterm prediction of forest fire danger rating. It was predicted that under the background of climate warming, the mean annual days of extremely high, very high, and medium forest dangers in study region in the 21st century all showed an increasing trend, while the mean annual days of high and low forest dangers were in adverse. Relative to the baseline period of 1961-1990, the mean annual days of extremely high and very high forest dangers in the 2040-2069 and 2070-2099 under the scenarios of SRES A2a and B2a would be increased by 43 and 36, and 62 and 61, respectively.